yes you can do this yourself for no money, but I strongly recommend having an expert service do it. Try Auto DCP. Just drag files into your dropbox, share and let them do all the work. [service.autodcp.com]

a small independent cinema near me uses that
i've taken quicktimes out of FCP to them,
and their DCPs looked pretty much how the show looked to me at home.
no idea what settings they used, my guess would be nothing special, just default,
of course if helps if you can see the results!

hang on, you're FCPX
i thought that was getting DCP support?
sorry i don't know much more than that.

I also recommend DCP-o-matic.
I've used it regularly for 2½ years and checked its DCPs carefully.
You can project them at a theater to confirm them on screen, or you can simply use the provided dumpxyz.exe program to examine the DCPs pixel by pixel.
The trick to making a good DCP is for you to understand how you've made, and viewed, your source file and then to convey this understanding to the DCP program. DCP-o-matic's user interface makes this natural. Going to a pro to make the DCP does not relieve you of that first responsibility.
DCP-o-matic is the creation of a smart young man, Carl Hetherington. It's wonderful that in our era of messy digital video standards he could pull it off, and that in our era of capitalist greed he would, as freeware.